1. Field of Invention
This invention relates to broadcasting computer files, specifically to broadcasting computer files using television.
2. Description of Prior Art
Transferring computer files has become a common part of modern life. Knowingly or unknowingly, people rely on computer file transfers whenever they send e-mail, receive e-mail, or use the World Wide Web.
File transfer is an integral part of the computer industry. Commercial software is delivered by transferring files from manufacturers to consumers using the Internet for electronic file transfers or magnetic or optical disks for physical file transfers. Encyclopedias are published as a set of files that are written onto an optical disk and delivered to consumers.
File transfer and, more specifically, file publishing is the most common use of the Internet and the Web. In fact, the Web was invented as a means to publish information needed by high energy physicists. Web sites are published by a wide variety of sources ranging from individuals (i.e., personal Web pages) to major news organizations. In reality, what is published are computer files that are placed on file servers connected to the Internet.
Although there are millions of Web sites they are not accessed equally as often. A small percentage of Web sites accounts for a large percentage of file access requests. For example the Web site of a major news organization, corporation, or government agency is “visited” much more often than an obscure personal Web page.
Although the Web is a two-way communications system there is a significant amount of activity that could be better served by a one-way system. For example, when a user “browses” the Web site of a news organization most of the data communications between his browser software and the site consists of file transfers or “downloads”. The communications pattern is “asymmetric” meaning that there is more traffic in one direction than in the other.
There are examples of asymmetric communications patterns on the Internet where the data communication is almost entirely in one direction. People who use e-mail to get “news alerts” or who subscribe to mailing lists are effectively requesting one-way communications from the Web site or list publisher. Streaming media and webcasting are other good examples. Applications like these could be provided by a true one-way communications system.
Television is a one-way communications system and several inventors have proposed ways to use television to broadcast data. Some proposals, including U.S. Pat. No. 6,268,889 to Kouri (2001) and U.S. Pat. No. 6,219,537 to James, et al. (2001) have disclosed methods of using the vertical blanking interval in an analog television signal to encode and transmit data. U.S. Pat. No. 6,556,247 to Ranta, et al. (2003) discloses a method of decoding data that is written into the horizontal overscan portion of the television image. All of these methods avoid modifying the television images that are visible to human viewers. As a result, these methods can support only low data transmission rates since they have a limited amount of bandwidth available for data transmission.
All of the proposals mentioned above require analog television transmission. Other proposals requiring analog television transmission are disclosed in U.S. Pat. No. 6,535,253 to Barton et al. (2003) and U.S. Pat. No. 5,737,026 to Lu, et al. (1998). A proposal disclosed in U.S. Pat. No. 6,549,241 to Hiori (2003) is one of many that require digital television transmission. All proposals that require a specific television transmission method suffer because of the Federal Communications Commission requirement for all broadcasters to switch from analog to digital television transmission by 2006. The methods requiring analog transmission will not be applicable after the transition. The usefulness of the methods requiring digital transmission will depend on consumer purchases of new equipment and new services offered by digital broadcasters.
A proposal disclosed in U.S. Pat. No. 5,790,937 to Gutle (1998) uses the bandwidth of a television channel to broadcast data. A proposal disclosed in U.S. Pat. No. 6,122,010 to Emelko (2000) uses a television signal to encode data. Both of these require special hardware to manipulate electrical signals and further suffer because they cannot transmit data and images at the same time.
Inventors have proposed methods of broadcasting data that manipulate television images rather than television signals. U.S. Pat. No. 6,078,360 to Doornhein et al. (2000), U.S. Pat. No. 3,984,624 to Waggener (1976), U.S. Pat. No. 6,512,835 to Nuamo et al. (2003) and U.S. Pat. No. 6,339,449 to Ikeda et al. (2002) disclose methods whereby data is encoded in the visible part of a television image by slightly modifying the image in a manner that is imperceptible to a human viewer. Disadvantages of these proposals are that they are complex and the data transmission rates are limited so that the image modifications are imperceptible.
Other methods have been proposed that manipulate television images in a manner that is perceptible to human viewers. U.S. Pat. No. 5,262,860 to Fitzpatrick, et al. (1993) discloses a method of displaying bar codes and characters that can be recognized by optical character readers and bar code readers. It suffers because the data transmission rate is limited due to the restricted data formats.
A proposal disclosed in U.S. Pat. No. 6,008,857 to Keery, et al. (1999) uses colors assigned to specific locations to represent data in a video frame. A disadvantage of this proposal is that it provides no means to reproduce a file having a specific name and a specific length. A second disadvantage is that the method proposed to assign colors limits the color combinations that can be used in an image.